Speech-Based E-Mail and Driver Behavior: Effects of an In-Vehicle Message System Interface

Article excerpt

INTRODUCTION

Driving is a complex, safety-critical task. However, most people considered it to be a familiar, even safe, everyday activity that presents no special problems for the experienced driver--so much so that drivers frequently choose to perform a variety of other tasks concurrently, such as carrying on conversations, tuning the radio, or eating.

Although these and similar activities have been found to be associated with increased accident risk (see Stevens & Minton, 2001; Stutts & Hunter, 2003), developments in in-car information and communication systems provide further possibilities for time-sharing. In addition to navigation displays, telephones, and various in-car entertainment systems, in-car computers that support all features associated with a standard Windows-driven laptop (e.g., G-Net's Auto PC) are now available, as are intelligent transport systems and wireless Internet. Such technology allows the driver access to a wide range of information sources and to perform a variety of additional tasks, effectively providing a mobile office. There are undoubted benefits associated with such systems (e.g., for those engaged in sales; Eost & Galer Flyte, 1998). However, if they are used while driving, safety may be compromised through competition for limited perceptual, cognitive, and/or response processing capacity (e.g., see Wickens, 1991, for a discussion of capacity limitations).

A related task, the use of cellular phones while driving, has been the subject of substantial recent research interest (for reviews, see Goodman, Tijerina, Bents, & Wierwille, 1999; Haigney & Westerman, 2001). Cellular phone use has been found to be associated with increased driver workload (Aim & Nilsson, 1994; Brookhuis, De Vries, & De Waard, 1991 ; Haigney, Taylor, & Westerman, 2000) and, consistent with this, degraded situational awareness (see Endsley, 1995, for a description of the concept of situational awareness, including the association with mental workload).

When using a cellular phone, drivers are less effective in their responses to events in the driving environment, such as braking in response to visual stimuli (Ahn & Nilsson, 1994), taking evasive action to avoid objects (Cooper et al., 2005), detecting leading car deceleration (Lamble, Kaurenen, Laakso, & Summala, 1999), and taking evasive action to a range of traffic scenarios (McKnight & McKnight, 1993). This may be part of a more pervasive reduction in drivers' interactivity with the driving environment and a tendency to execute either the current, or a previously determined, "schema." In support of this proposition, Haigney et al. (2000) found that the variability of gas pedal movement was reduced during cellular phone use, and Brookhuis et al. (1991) found a decrease in variability of lateral position when drivers were using a mobile phone, particularly under motorway driving conditions. Such reduced responsiveness to external events may be an involuntary result of increased competition for attentional resources when using a cellular phone. Alternatively, drivers may be aware of threats to performance when using a cellular phone, and this may be part of a process of strategic control designed to facilitate timesharing.

There is some limited evidence that drivers compensate for demands associated with cellular phone use by increasing safety margins. Haigney et al. (2000) and Alm and Nilsson (1994) found speed reductions when drivers were taking a phone call. However, Aim and Nilsson (1994) found this only in an "easy" driving condition, and this was not replicated by Aim and Nilsson (1995). Cooper et al. (2003) found that drivers were more cautious in response to changing traffic lights when engaged in a cellular phone task. Nevertheless, cellular phone use has been found to be associated with increased risk of accident involvement (Redelmeier & Tibshirani, 1997; Violanti, 1998), and legislation has been enacted in several countries to restrict the use of cellular phones by drivers. …